Electrical measuring instrument



2 Sheets-$heet 2 INVENTOR PTTORNEY .P P iflunu l nim- H 1 I nf Jose 0 14Leyy J. W. LEGG ELECTRICAL MEASURING INSTRUMENT Filed Sept. 26; 1925Oct. 9, 1928.

.llllilll WITNESSES:

' Patented Oct; 9,1928.

* unireo s'rArEs PATENT 1 OFFICE.

J'GSEPI-I W; LEGGQOFWIL INsB'JRG, tennnsYLvAnIA, ASSIGNOR T WESTINGHOUSEnLnornIc & MANUFACTURING COMPANY, a oonron-e'rron or PENNSYLVANIA'ELECTRICAL mnasunrne INSTRUMENT.

Application filed September 26, 1925. 7 Serial No. 58,815.

My invention relates to measuringinstru- One object of my invention isto provide an instrument, of the above-indicated charaster that shallrequire substantially'minimunicurrent consumption for its operation.

Another object of my invention is to provide an electrical measuringinstrument embodying relatively movable elements that shall movedifierent distances in opposite directions in response to equal andopposite energization of one of the elements.

Another obj ect of my invention is to provide an instrument that shallembody a scale having an off-center zero position and that Y shallrepresent at least one range of values in one direction and a of valuesin the opposite direction from its zero position, together with movableindicating means for co-operation therewith.-

plurality of ranges Another object of my invention is to proi vide anovel means for simply; economically and accurately mounting thestationary and movable elements of a meter in relative positions. I

Another objectof my invention is to provide a simple and economicalcasing struc ture for an GlQCtTlCi ll'11132151111112;JDStIUHlGIlt-' thatshall comprise parts which are definitely construct-ed in accordancewiththe electrical characteristics of the operating elements oitheinstrument supported thereby.

Another object of myinvention is to provide an electromagnet of novelconstruction whereby a core member of substantially. U-

shape be retained in fixed relation to a supporting structure adjacentto the'poleends thereof and that shall embody a removable sectionintermediatesaid ends'for the reception of an energizing coil. g

further object ofniy invention is to provide an, electrical measuringinstrument that shall be simple and durable in construction, economicalto manufacture and effective in its operation.

lVit-h such objects in view, as 'well as other advantages which may belIlClClQIlll to the utilization of the improvement my in ven tionconsists in the parts and combinations thereof hereinafter,set'forth andclaimed instrument for the purposes into practical with theunderstanding that the several ments and particularly to electricalmeasf necessaryelements-constituting thesame may uring instruments ofthe polarlzed-vane be varied in proportions, texture and artypgrangernent-without vdeparting from the na+ ture and scope of theinvention.

Heretofore, voltmeters for measuring the devices to be operated by thebatteries. This condition, unknown to those not versed in electricalmatters but who Wish to operate such devices and may know, in a generalway, vthat the battery voltages should be maintained above certainvalues for satis factory results, sometimes drains the batteries inarelatively short time for no apparcut-reason. i

It is one ofmy aimsto remedy the above condition by providing aninstrument that may be used freely, even by those not having' muchknowledge of electrical devices, and that shall require substantiallyminimum current for its operation. 1

"However, other aims, as outlined in the objects stated-above, arecontemplated to provide an instrument of compact and economicalconstruction, neat appearance and very efiective operation.

Accordingly, in practicing my invention, I provide an instrument inwhich the am pere turns of the energizing-magnet are so relatedto thebatteries from whichthey obtainlfcurrent, in which the magnet pole endsare-so constructed'relativeto the mov-v able element, in which the d al1s sofmarked',

in which the parts of a two-part casing are partsof the instrument, andin which-other stantially minimum current for its operation and'toother-wise ,obtaina highly improved for which it is adapted; I I i v Inorder to make the invention more clearlyv understood, companyingdrawings for carrying the same effect without limiting the so related toeach other and to the other means are shown in the 'acimprovements inthese useful a aplications to the particular constructions which, forthe purpose of explanation, are made the sub ject of illustration.

Figure 1, of the accompanying drawings, is a front or face View of anelectrical measuring instrument. constructed in accordance with myinvention,

Fig. 2 is a view taken along the line 11-41 of 1,

Fig. 3 is a view taken along the line lIl[-III of 2, i

Fig. i is a detail perspective viewof a portion of the instrument, V

and partially in section along the line V-V of Fig. 6, of modified formof my invention, and r Fig. 6 is a rear elevation or back view of thedevice shown in Fig. 5.

-Referrihgto Figs. 1 to 4, inclusive, the instrument comprises, ingeneral, a casing 1, in which are disposed a dial plate 2, a pointer 3,'a movable element or magnetizable vane 5, a movement support 6, and apermanent control magnet i" for the Vans 5, and to which casing areattacheda window plate 9, an electromagnet 10 and mounting studs 11. VThe casing l'is constructed of a non-mag netic material,preferably of asingle Jiece of relatively-thin sheet brass, to be of relatively shallowsubstantially cup-shape and is provided around its open-end perimeter,with an outi'vardly projec ing integral flange.

A ring member 14, press-fitted into the open end of the casing 1, andanother ring member 15', press-fitted. into a tubularfportion'of thering '14, areprovided with inwardly-projecting flange portions betweenwhich the window plate-9 is held in position.

Each studll comprises a. threaded shank portion, a head 18 and aprojecting portion 17 integrally united to each other.

Thepermanent control magnet '2' is preferably constructed of relativelythin sheet formation to lie in relatively close parallelplane relationto the rear wall of the nonmagnetic casing'to which it is secured bythe, heads 18-01 the studs .11 which extend through the casing .1. Theheads 18 also.

serve as positioning and spacing means for the dialpl'ate'2, which issecured inposition by swaging over the ends of the portions The" studs11 are held in position by lock washers 1.9 and spanner nuts 28 thereonat the side of the casing 1. A

.Theoial pl'ate 2, constructed of material similar to that ofthe casing1, is provided with an opening in which a portion ofthe movement supportwhich the pointer 3 extends, and is provided with a plural-part scale,represented by the -lettersA,B and C for co-operati'on with the pointer3 7 he zeroor inoperative position of the the o1 posite direction fromthe zero Fig. 5 is a view, partially in side elevation of the portions20 and pole ends 21 of equal lengths and straight, rounded symmetrically6 is disposed and through scale is disposed eccentric to, or at one sideoi, the center thereofifor a purpose to-be hereinafter more fullyexplained, and is graduated, one direction of the pointer 3 from thiszero position thereof, in accordance with at least one range of values Aand, in

position, in accordance with a plurality of ranges of values, as B'-C.

The elec ro-magnet 1O comprisesa core member of iron or iron alloyhaving very little residual magnetism and is of substantiallyU-shapeembodying; side portions 20 and21, around the portion 21 of which a coilor -i .inding 22 is disposed, and a separable end portion 241-. The coil22 maybe placed around the portion 20 or be slightly modified, or theend portion 21% modified, for

The electromagnetl-O is secured to the nonmagnetic rear wall .25 of thecasing 1, as by projections 26 and 2'. ,on the portion 20, andprojections 29 which extend through ooenin s in to Wall 25 and are.preferably held position by bodies ot 'solder 81 L junctures of theintercepting surfaces.

The vane 5 is of substantially ellipsoidal flat sheet form disposed inclosely parallel plane relation to the'control magnet *1' having' itsmajor or magnetic axis normally disposed at substantiallyright angles,or trans verse, to the magnetiofield axis of the electromagnet 10between the aoleenda-oi' ends having the projections 2627. and 29 30,

21 and'subst in line with the nia netic axis of the flux path betweenpole e s 32 and 33 of the con trol. magnet 7. l

The above-described of the electromagnet portions 20 or otherwiseuniformly r formed, asin the usual st'ruc mer s of sgeneral type, wouldcausetbe magnetic ;is of the vane to liein horizontal position, asviewed. in 3, when the elroznagnet isdeen rg ized, and the vane'5 feetabout its nnt axis equal distances for equal degrees of energization ofthe electroniagi net 10 in opposite directionsw However, by having theprojections 26 and 29 relatively short-and the diagonally tures ofinstru-.

opposite projections 27 and 80 relatively.

long, the tens 5 normally lies slightly on the aboveenentionedhorizontal. position, as shown in Fig. 3 and equal energization of theeleotromagnet in opposite directions by and 30, on the portion 21.-

a: screw,

round and between the ciall'y structure, with the" currents ofrelatively large magnitude defleets the vane unequal distances. Moreparticularly, the above-described arrangement of the pole tips orprojections 26, 27', 29

and 30, or one equivalent thereto,fimproves the operatingcharacteristics of the device in that equal increases in the magnitudeof the current traversingthe coil 22 produces, over a greater range thanhas heretofore been possible, substantially equal deflections of thepointer 3. This result is effected due to the fact that the endot poletip 26, for example, is removed some distance fromfthe plane of the vane5. Accordingly, said pole tip 26 is prevented from exercisingits'ma'Ximum effect on the vane 5 as it moves in a clockwisedirection,,Fig; .3, and as a result, the increments of vane movement aresubstantially uniform even though the end thereofhas passed in aclockwise direction, Fig. 3, beyond the line joining the-axis of saidvane and the pole tip 26.

The projections 26,27, 29 and, 30'beingthus, provided for a particular,new principle of operation are further utilized, 1n a mechanical sensefor positionin the moving and stationary operating parts relative toeach other to a fine degree of: precision which may be elfectedquicklyin assembling are mounted tainedin accurate relation. to each other toinsure continued eiie tive operation of the instrument. The pointer. 3may be provided; with a counterbalance weight or damping member 37.

0 measure very small currents Iemploy arelativeiy great'number ofshortturns of fine wire of much lower'resi'tance than in any instrumentwhich, tomy 'liIlOWlGClQ'GllflS similarly been employed in batterycircuits.

In operation, when it isdesired to measure direct-current orbatteryvoltages, not be yond a maximum of fivevolts, the coil 22 isconnected to a circuit by leads (not shown) to sodirect the current andthe flux of the clectromagnet 10 as to deflect the pointer 3 to the leftof its zero position along the scale A, as viewed in Fig. 1.

WVlien it desired to measure a similar voltage, not beyond a maximum ofseven or eight volts of opposite polarity, the direction;

of voltages and on each range. The ordinary formsof in- "struments ofthis general type usually .ein-

sci

. provi (led Y 44 and pointed and I oi-shaped support 6. Thus, all ofthe operating parts are mainof current in the/coil 22 being reversed,the pointer swings over the scale C.

:By providing a suitable resistor (not shown) in circuit withthe coil22and energizing the latter in the .samedireotion as when employingthe,scale C, the pointer may be caused to swing ,overthe scale B to indicateup, to maximum of about'one hundred and iit'ty volts, in the particularinstrument shown.

The

instrument is therefore extremely flexiblcin its adaptation to differentranges ives very accurate readings ploy scales of equal values .oneither, side of zero and are generally and approximately accurate, beingactually employed more to indicate only the presence, and direction ofvoltagerather' than to 'obtain"-closelyac-" curate ineasuresof itsvalue. V

In the modification of my invention shown in Figs-5 and 6,'1n whichcorresponding parts are designated by corresponding referencecharacters, the construction and operation are'substantially the same asabove deing casing 0 of substantially cup-shape is I with its open endagainst the closed end of the casing 1, whereby the nonmagz netic rearwall '25 votthe -casing constitutes intermediate supporting wall in thecompositecasing of this structure, and a tine-wire resistor winding 41is mounted in the self-contained unit, In'this unit also. a air ofmounting. studs 11 are extended 'ough the rear wall of the insulatingcasing to for cooperation with nuts 422.. a clip (not shown), 7 I ITerminalelements 45 and 46 are mounted on the rear wall of theinsulatingportion 40 of the composite or v multi-part casing. for

connecting the coil 22 and tl e'resistor 4:1 to

an outside or battery circuit.- v v In the above-described structure,the magiocd, eXceptt-hat an auxiliary insulatother minor elements,t'orliol'ding the casing 40 to the casingfl. and unit 1nstrument,-asacwhole, on a panel or other support net-ic or flux-employing operatingparts are electrically effectively mechanically and 1', t0 'llt mountedin the non-magnetic casing unaffected thereby and the current-conductingterminals arepmounted on the casing 44) Without the requirement foradditional in--' sulation which Would be necessary ifthe (as ing4.0;wereof metal.

' Thus, a neat, compact, flexible and self contained unit of economicalconstruction and effective operation is provided having its'parts ofsuchtexture and relation as to require them to be of substantially mini'mum number'and of niaximum'simplicityi I claim as my invention;

1. An, electrical measuring instrument comprising a movableflux-responsive ele ment, biased toward a predetermined zero position,and an actuating electroinagnet therefor including a core membershapedto magnetically move said element farther from said position whenenergized in one i direction than when "equally energized in theopposite direction.

2. An electrical measuring instrument comprising a movableflux-responsive eloment biased toward a predetermined zero position, andan actuating electromagnet therefor including aicore member, themagnetic axis between the poles of which e2:-

tends transversely adjacent to the magnetic aXisofthe element in thede-energized condition of the magnet, the pole ends of the magnet beingconstructed to so affect the flux thereof as to move the element fartherfrom said position when the magnet is energized in one direction thanwhen it is equally energized in the opposite direction.

3. An electrical measuring instrument comprising a movableflux-responsive ele ment biased toward a predetermined zero position,and an actuating electroinagnet therefor including a core member, themagv netic axis between the poles of which er-ztends transverselyadjacent to the magnetic of the element in the de-energized condition ofthe magnet, one of the pole ends of the magnet being shaped to deflectthe flux laterally from its normal axis for effecting movement of theelement farther from said position when the magnet is energized in onedirection than when it is equally energized in the opposite direction.

4. An electrical measuring instrument comprising relatively movableflux-exchanging elements biased toward a zero relative position in whichthe flux axes thereof are angularly related, one of said elements including a magnetizable member having a pole end portion shapedto soaffect the flux between the elements-as to cause the same to moverelatively a greater distance from said zero position when one of theelements is energized in one direction than when it is equally energizedin the opposite direction;

.5. An electrical measuring instrument comprising a movableflux-responsive ele inent biased toward a predetermined zero position,and an actuating electromagnet therefor including a core member the magnetic axis'between the poles of which eX tends transversely adjacent tothe magnetic axis of the element in the deenergized condition of themagnet, the pole ends of the core member each having projecting portionsof different lengths for effecting move ment of the element a greaterdistance from said position when the magnet is energized in onedirection than when it is equally enei'gized in the oppositedirection.

6. A measuring instrument comprising a scale having an eccentric'zeroposition thereon, the scale being marked in one direction from saidposition to represent one range of values and in the oppositedirectionfrom said position to represent a plurality of 79 ranges ofvalues, and movable indicating means for co-ope'ration with the scale inac cordance with values of each of said ranges.

7. An electrical measuring instrument com arisin a movableeleinent afield-ma 7 CJ 7 h a movable element atone side of said wall, 9

a 'fieldeinagnet core member at the other. side of said wall having apole portion extending therethrough and a beariii support for theelement at said other side having a portion fitting said pole portion.

10. Anelectrical measuring instrument comprising a casing embodyingfront and rear members of -substantially cup shape, the closedend'of'one being disposed in contacting relation with the open end of theother whereby saidclosed end constitutes an intermediate wall of thecasing, said front member being of vrelatively-thin non-magneticinetal,'inagnetic-flux operated and of' er atingel'ements siuopoi'tedon'the respective 10a sides of said non-magnetic intermediate wall, saidrearinember being of insulating material, and conducting terminals ofthe instrument supported on said insulating rear member. V

111. The combination with an oscillatory magnetizable member to aselected position, of electromagneticmeans comprising a pole il? withrespect to which one end of said inemberis movable", response to equalincreases in the magnitude of theCLII'lElltlli'ZWGTSlIlg saidelectromagnetic means, controlling movement of said member bysubstantially equal increments after said one end of said' member hasmoved 1 j instrumentof substantially lJ-shapehaving said pole tip, in

from said position to a region beyond line passing through the axis ofsaid'inember and said pole tip. V r

12; The combinationwith an osc llatory magnetizable member biased to aselectedpos non, of electromagnetic means compris, ing a plurality ofspaced pole tips with respect to which one end of said member ismovable, the distances between said one end of said member and therespective pole tips 4 the lines passing through being difierent whenthe longitudinal axis of said member coincides, respectively, with thevaxis thereof and said pole tips.

13. The combination with an oscillatory magetiZa-ble member biased to aselected p0- sition, of electromagnetic means comprising a pluralityofspaced pole tips with respect to which one end ofsaid member, ismovable,

the ends of said-pole tips beingspaced different distances from theplane of said member. a I

In testimony whereof, I haye hereunto subscribed my name, this first dayof September, 1925.

' JOSEPH W. LEGG.

